1. Field of the Invention
The present invention relates to a touch roll, a main roll, a sheet film casting apparatus, a fine pattern transferring apparatus and a sheet film. In particular, the present invention relates to a roll or the like which has multiple rubber rolls inside its external cylinder.
2. Descriptions of the Related Art
Heretofore-known sheet film forming apparatuses include an apparatus configured to form a sheet film by sandwiching a molten resin W poured out of a T-die 401 between a main roll 403 and a touch roll 405 (see FIG. 1).
The touch roll 405 of the sheet film forming apparatus includes: an internal cylinder member 407; a rubber roll; eccentric side plates; and a cylindrical metal-made elastic external cylinder 409 having a thin structure. The internal cylinder member 407 has shaft portions in its two ends and is rotatably supported by these shaft portions with bearing parts, respectively. The rubber roll is attached to an outer peripheral surface of the internal cylinder member 407. The eccentric side plates are rotatably attached to the shaft portions in the two ends of the internal cylinder member. The cylindrical metal-made elastic external cylinder 409 is rotatably supported by the eccentric side plates, has the inner diameter larger than the outer diameter of the rubber roll, accommodates the rubber roll in its inside, and has a part of the inner peripheral surface in contact with a part of the outer peripheral surface of the rubber roll. The configuration of the touch roll is disclosed in Japanese Patent Application Laid-Open No. 2007-83577.
The conventional type of sheet film forming apparatus has the following problem. Because the rigidity of the touch roll 405 is insufficient, the touch roll 405 is elastically deformed when the resin W is sandwiched between the main roll 403 and the touch roll 405. This makes it highly likely that the touch roll 405 may be incapable of pressing the sheet film with an even pressing force in the width direction of the sheet film.
This problem becomes conspicuous particularly in a case where the main roll and the touch roll are made longer in length for the purpose of forming a resin into a wider sheet film, and in a case where the main roll and the touch roll are heavier in mass.